Antenna system



April 17, 1956 M. E. HlEHLE 2,742,641

ANTENNA SYSTEM Filed Jan. 19, 1951 Inventor: Michael E. Hiehle,

His Attorney- United States PatentO ANTENNA SYSTEM Michael E. Hiehle, Inglewood, Califi, assignor to General Electric Company, a corporation of New York Application January 19, 1951, Serial No. 206,819

7 Claims. (Cl, 343-791) The present invention relates to improvements in antennas, and relates: particularly to improvements in means for energizing sleeve-type antennas.

Sleeve type antennas are well known in the art for their capabilities. in radiating a broader band of frequencies than a dipole antenna. One form of sleevetype antenna comprises a dipole and a conductive sleeve partially enclosing the central portion of the dipole. In order to provide balanced excitation or energization of the sleeve-type antenna from an unbalanced or single ended source, it is necessary to use a balun.

By a single ended source is meant a source having one terminal which is connected to ground or other fixed potential point. By a balanced input connection is meant an input connection in which neither terminal is connected' to ground or other fixed potential point. A balun is a device usually made from sections of coaxial transmission line to convert a single ended input connection into a balanced input or push-pull connection so that dipoles, sleeve type antennas, and the like may be supplied with balanced excitation from single end sources.

An object of the present invention is to eliminate the need for a balun to providev balanced excitation to sleevetype antennas.

Another object of the present invention is the provision of means integral with sleeve type antenna structures whereby balanced: energization or feed to a sleevetype-antenna is provided from a single ended source.

A further object of the present invention is to provide improvements in the antenna systems and structures.

The features of my invention which I believe to be novel are, set forth with'particularity in the appended claims. My invention itself, however, together with fur.- ther objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings in which Fig. 1 is a sectional view of an embodiment of my invention by means of which a sleeve-type antenna is supplied with balanced excitation from an unbalanced or single ended input connection; Fig. 2, a sectional view of a folded dipole embodiment of my invention.

An exemplary embodiment of my invention comprises a sleeve-type antenna in which the radiating conductor is a single conducting member and in which the sleeve member surrounding the radiating member forms a halfwave section of coaxial transmission line with a portion of the radiating conductor so that when energization is applied to one side of the antenna between the radiating conductor and the end of the sleeve member corresponding therewith, energization of opposite phase is applied to the other side of the radiating conductor through the aforementioned half wave section of transmission line. Accordingly, balanced excitation is applied to a sleeve-type antenna from a single ended SOUIC6.r

In Fig. 1 is shown a sleeve-type antenna 1 excited in balanced phase from a single ended source in accordance with my invention. The sleeve type antenna in this figure comprises a single radiating conductor 2 Ice surrounded by a tubular or cylinder conductor member 3 which forms a section of coaxial transmission line having an axial length equal to approximately a half of a wavelength at. the frequency of operation of the antenna. relationship with respect to the sleeve member 3 by the insulator 4 which, for example, may be polystyrene.

' A conventional coaxial transmission line 6 connected to a source of energization 5 is used to energize thesleeve-type. antenna. Inner conductor 7 of the transmission liue is connected adjacent. one end of the sleeve member to the radiating conductor 2. The outer conductor 8 of the transmission line 6 is connected to the sleeve member 3. Since sleeve member 3 and the radiating conductor 2 form a half-wave section of transmission line, the other end of the radiating conductor 2. is energized in opposite phase from the end to which the. transmission line is immediately connected. Accordingly, the radiating conductor 2 is energized in pushpull or balanced. phase without the need for a balun of the kindv described above. The sleeve member 3 may be connected; at its center to a support 9 which preferably is. grounded.

The overall length of the radiating conductor 2 may have values; from half of a wavelength to a; wavelength at the operating frequency of the antenna system depending upon the particular radiation characteristics desired. The electrical, length of the sleeve and the portion of the radiating conductor enclosed by the sleeve should be made electrically substantially half of a wavelength at the frequencies of operation of system to obtain balanced excitation for the antenna system. It is well known to those in the art that when an insulating medium is used: between the inner and outer conductors of a section of transmission line, the mechanical length, of the line. corresponding to half of a wavelength is less than shown in Fig. 1 over a frequency range from 175 to 211 megacycles showed negligible beam shift due to unbalance. of energization or feed of the antenna.

in order to provide more uniform impedance over a wider band width and to provide lightning protection the folded dipole embodiment of my invention shown in Fig. 2 maybe used in this figure additional conductors. E0 and 11 are connected between the ends of the. radiating conductor 2; and a point 12' on the sleeve. member 3 which preferably is grounded through the support 9.

To provide unidirectional response, a conductive sheet or reflector may be used in conjunction with the constructions of Fig. 1 or 2 in a manner well known to those skilled in the art.

Accordingly, it is seen that I have provided an improved antenna system and structure in which the need for conventional baluns for providing balanced excita tion to sleeve-type antennas is limited. The invention has many uses. vision systems.

While I have shown particular embodiments in my invention, and suggest certain modifications that may be made therein, it will, of course, be understood that I do not wish to be limited thereto since various other modifications will readily occur to those skilled in the art. I, therefore, contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An antenna system comprising a dipole including The radiating conductor 2 is held in insulated.

One particular use would be in telea pair of radiating end portions, a tubular conductive member surrounding a center portion of said dipole between said radiating end portions and in insulated relationship therewith, means for exciting one of said portions with respect to said tubular conductor member, said tubular conductor member having a length to form with said center portion of said dipole a section of transmission line whereby the inner conductor of said transmission line excites the other radiating portion of said dipole with respect to said tubular conductor.

2. A radiating structure for use with radio systems comprising a conductive sleeve member, a radiating conductor partially enclosed by said sleeve member, the portion of said radiating conductor enclosed by said sleeve member being in insulated relation to said sleeve member, said radiating conductor having portions extending from each end of said sleeve member, excitation means including a transmission line having one conductor connected to said radiating conductor adjacent one end of said sleeve and the other conductor of said transmission line connected to said sleeve member at said end whereby balanced excitation is supplied to said radiating conductor.

3. A radiating structure for use with radio systems comprising a conductive sleeve member, a radiating conductor partially enclosed by said sleeve member, said radiating conductor being in insulated relation to said sleeve member and forming therewith a half-wave section of coaxial transmission line, said radiating conductor having portions which extend from each end of said sleeve member, excitation means including a coaxial transmission line having an inner conductor connected to said radiating conductor adjacent one end of said sleeve, the outer conductor of said transmission line connected to said sleeve member at said end whereby balanced excitation is supplied to said radiating conductor.

4. A radiating structure for use with radio systems comprising a conductive sleeve member, a radiating conductor partially enclosed by said sleeve member, said radiating conductor being in insulated relation to said sleeve member and having portions extending from each end of said sleeve member, excitation means including a grounded coaxial transmission line having the inner conductor thereof connected to said radiating conductor adjacent one end of said sleeve and having the outer conductor thereof connected to said sleeve member at said end, said sleeve member having an axial length of the order of a half wavelength at the operating frequency of said radiating structure to excite said other end of said radiating structure in opposite phase.

5. A radiating structure for use with radio systems comprising a conductive sleeve member, a radiating conductor partially enclosed by said sleeve member, means for maintaining said radiating conductor in insulated relationship with respect to said sleeve member, said radiating conductor extending the same distance beyond each end of said sleeve member and having an overall length less than about a wavelength at the frequency of operation of said structure, the portion of said radiating conductor enclosed by said sleeve member and said sleeve member forming a section of approximately half-wave transmission line, excitation means including a grounded coaxial transmission line having the inner conductor thereof connected to said radiating conductor adjacent one end of said sleeve member and the outer conductor thereof connected to said sleeve member at said end.

6. A radiating structure for use with radio systems comprising a conductive sleeve member, a radiating conductor partially enclosed by said sleeve member, means for maintaining the enclosed portion of said radiating conductor in insulated relationship with respect to said sleeve member, said radiating conductor having portions extending beyond the ends of said sleeve member and having their ends connected to the outside of said sleeve member, excitation means including a transmission line having one conductor connected to said radiating conductor adjacent one end of said sleeve and the other conductor of said transmission line connected to said sleeve member at said end whereby balanced excitation is supplied to said radiating conductor.

7. A radiating structure for use with radio systems comprising a conductive sleeve member, a radiating conductor partially enclosed by said sleeve member, means for maintaining the enclosed portion of said radiating conductor in insulated relationship with respect to said sleeve member, said radiating conductor having portions extending equal distances beyond the ends of said sleeve member and having their ends connected to an outside midpoint of said sleeve member, excitation means including a transmission line having one conductor connected to said radiating conductor adjacent one end of said sleeve member and the other conductor of said transmission line connected to said sleeve member at said end whereby balanced excitation is supplied to said radiating conductor.

References Cited in the file of this patent UNITED STATES PATENTS 2,229,078 Hansel] Jan. 21, 1941 2,234,234 Cork Mar. 11, 1941 2,239,724 Lindenblad Apr. 29, 1941 2,267,951 Roosenstein Dec. 30, 1941 2,476,949 Adams July 26, 1949 2,509,253 Schriefer May 30, 1950 

